From: Ben Hutchings Date: Wed, 21 Aug 2019 00:05:30 +0100 Subject: intel-iommu: Add option to exclude integrated GPU only Bug-Debian: https://bugs.debian.org/935270 Bug-Kali: https://bugs.kali.org/view.php?id=5644 There is still laptop firmware that touches the integrated GPU behind the operating system's back, and doesn't say so in the RMRR table. Enabling the IOMMU for all devices causes breakage, but turning it off for all graphics devices seems like a major weakness. Add an option, intel_iommu=igpu_off, to exclude only integrated GPUs from remapping. This is a narrower exclusion than igfx_off: it only affects Intel devices on the root bus. Devices attached through an external port (Thunderbolt or ExpressCard) won't be on the root bus. Signed-off-by: Ben Hutchings --- Documentation/admin-guide/kernel-parameters.txt | 2 ++ drivers/iommu/intel/iommu.c | 14 ++++++++++++++ 2 files changed, 16 insertions(+) --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1837,6 +1837,8 @@ bypassed by not enabling DMAR with this option. In this case, gfx device will use physical address for DMA. + intgpu_off [Default Off] + Bypass the DMAR unit for an integrated GPU only. forcedac [X86-64] With this option iommu will not optimize to look for io virtual address below 32-bit forcing dual --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -54,6 +54,9 @@ #define CONTEXT_SIZE VTD_PAGE_SIZE #define IS_GFX_DEVICE(pdev) ((pdev->class >> 16) == PCI_BASE_CLASS_DISPLAY) +#define IS_INTGPU_DEVICE(pdev) (IS_GFX_DEVICE(pdev) && \ + (pdev)->vendor == 0x8086 && \ + pci_is_root_bus((pdev)->bus)) #define IS_USB_DEVICE(pdev) ((pdev->class >> 8) == PCI_CLASS_SERIAL_USB) #define IS_ISA_DEVICE(pdev) ((pdev->class >> 8) == PCI_CLASS_BRIDGE_ISA) #define IS_AZALIA(pdev) ((pdev)->vendor == 0x8086 && (pdev)->device == 0x3a3e) @@ -351,6 +354,7 @@ int intel_iommu_enabled = 0; EXPORT_SYMBOL_GPL(intel_iommu_enabled); static int dmar_map_gfx = 1; +static int dmar_map_intgpu = 1; static int dmar_forcedac; static int intel_iommu_strict; static int intel_iommu_superpage = 1; @@ -360,6 +364,7 @@ static int iommu_skip_te_disable; #define IDENTMAP_GFX 2 #define IDENTMAP_AZALIA 4 +#define IDENTMAP_INTGPU 8 int intel_iommu_gfx_mapped; EXPORT_SYMBOL_GPL(intel_iommu_gfx_mapped); @@ -445,6 +450,9 @@ static int __init intel_iommu_setup(char } else if (!strncmp(str, "igfx_off", 8)) { dmar_map_gfx = 0; pr_info("Disable GFX device mapping\n"); + } else if (!strncmp(str, "intgpu_off", 8)) { + dmar_map_intgpu = 0; + pr_info("Disable integrated GPU device mapping\n"); } else if (!strncmp(str, "forcedac", 8)) { pr_info("Forcing DAC for PCI devices\n"); dmar_forcedac = 1; @@ -2890,6 +2898,9 @@ static int device_def_domain_type(struct if ((iommu_identity_mapping & IDENTMAP_GFX) && IS_GFX_DEVICE(pdev)) return IOMMU_DOMAIN_IDENTITY; + + if ((iommu_identity_mapping & IDENTMAP_INTGPU) && IS_INTGPU_DEVICE(pdev)) + return IOMMU_DOMAIN_IDENTITY; } return 0; @@ -3325,6 +3336,9 @@ static int __init init_dmars(void) if (!dmar_map_gfx) iommu_identity_mapping |= IDENTMAP_GFX; + if (!dmar_map_intgpu) + iommu_identity_mapping |= IDENTMAP_INTGPU; + check_tylersburg_isoch(); ret = si_domain_init(hw_pass_through);